Gypsum panels, systems, and methods

ABSTRACT

Gypsum panels, sheathing systems, and methods of making and using the same are provided. A gypsum panel includes a gypsum core associated with a first fiberglass mat having a continuous barrier coating, the coating penetrating a portion of the first fiberglass mat opposite the gypsum core, wherein gypsum penetrates a remaining fibrous portion of the first fiberglass mat such that voids in the first fiberglass mat are substantially eliminated. A building sheathing system includes at least two gypsum panels and a seaming component to provide a seam at an interface between the gypsum panels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/180,589, filed on Jun. 13, 2016, which is a continuation of U.S.patent application Ser. No. 15/014,821, filed on Feb. 3, 2016, whichclaims priority benefit of U.S. Provisional Application No. 62/111,357,filed Feb. 3, 2015, which are each incorporated by reference herein.

FIELD

The present invention relates generally to the field of panels andsystems for use in building construction, and more particularly togypsum panels and systems of gypsum panels having water-resistive andair-barrier properties.

BACKGROUND

Many modern building codes require the use of barriers in constructionto protect the building from air and water penetration. For example,building codes in eastern Canada and the northeastern United States nowrequire air barriers to be used in all construction. Moreover, theexisting International Building Code/International Residential Code(IBC/IRC) requires the use of a water-resistive air barrier for all newconstruction. Water-resistive air barriers may be formed from a varietyof materials and structures and applied to the surface of constructionsheathing materials (e.g., gypsum panels, oriented strand board (OSB)panels).

Traditionally, three types of water-resistive air barriers may be usedto meet building codes. First, fabric-type membranes, or “wraps,” may beused to cover the surface of building sheathing panels. However, thesefabric wraps are typically unable to withstand wind conditions, sufferfrom drooping, and are difficult to install at heights. Moreover, thestandard method of attaching such fabric membranes to sheathing panelsis stapling, which compromises the effectiveness of the membrane as anair or water barrier.

Second, a liquid coating water-resistive air-barrier membrane may beapplied to sheathing panels. However, these liquid coatings must beapplied in the field by qualified contractors, which is time intensiveand costly. Moreover, although liquid coatings serve as an effectivewater barrier, they provide low water vapor permeance, which affects thewall's ability to dry should it get wet during service (e.g., aroundwindow penetrations, flashing).

Third, self-adhered, or “peel and stick,” water-resistive air-barriermembranes may be applied to sheathing panels. However, theseself-adhered membranes are generally not permeable and therefore are notan option in many projects, because the architect or engineer mustaccount for this impermeability in designing the building, to preventthe potential for moisture being trapped inside the wall cavity.Furthermore, self-adhered membranes require the sheathing panels to bedry and often primed prior to application, which significantly slowsdown the construction process.

Accordingly, it would be desirable to provide improved externalsheathing panels and building sheathing systems having water-resistiveand air-barrier properties, as well as methods of making such panels.

SUMMARY

In one aspect, a gypsum panel is provided, including a gypsum coreassociated with a first fiberglass mat having a continuous barriercoating, the coating penetrating a portion of the first fiberglass matopposite the gypsum core, wherein gypsum crystals of the gypsum corepenetrate a remaining fibrous portion of the first fiberglass mat suchthat voids in the first fiberglass mat are substantially eliminated.

In another aspect, a building sheathing system is provided, including atleast two gypsum panels and a seaming component configured to provide aseam at an interface between at least two of the gypsum panels. Eachgypsum panel includes a gypsum core associated with a first fiberglassmat having a continuous barrier coating, the coating penetrating aportion of the first fiberglass mat opposite the gypsum core, whereingypsum crystals of the gypsum core penetrate a remaining fibrous portionof the first fiberglass mat such that voids in the first fiberglass matare substantially eliminated.

In yet another aspect, a method of making a gypsum panel is provided,including depositing a gypsum slurry onto a surface of a firstfiberglass mat opposite a continuous barrier coating, the coatingpenetrating a portion of the first fiberglass mat, and allowing thegypsum slurry to set to form a gypsum core. The gypsum slurry penetratesa remaining fibrous portion of the first fiberglass mat such that voidsin the first fiberglass mat are substantially eliminated.

In still another aspect, a method of constructing a building sheathingsystem is provided, including installing at least two gypsum panelshaving an interface therebetween, wherein gypsum crystals of the gypsumcore of each panel penetrate a remaining fibrous portion of the firstfiberglass mat such that voids in the first fiberglass mat aresubstantially eliminated and applying a seaming component at theinterface between the at least two of the gypsum panels.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, which are meant to be exemplary and notlimiting, and wherein like elements are numbered alike.

FIG. 1 is a cross-sectional view of a fiberglass faced gypsum panelhaving water-resistive and air-barrier properties.

FIG. 2 is a cross-sectional view of a fiberglass faced gypsum panelhaving water-resistive and air-barrier properties.

FIG. 3 is a perspective view of a building sheathing system havingwater-resistive and air-barrier properties.

FIG. 4A is a side view of an experimental apparatus used for thehydrostatic head tests of Example 1.

FIG. 4B is a top view of an experimental apparatus used for thehydrostatic head tests of Example 1.

FIG. 5 is a graph showing the results of the hydrostatic head tests ofExample 1.

FIG. 6A is a micrograph of a cross-section of the center region of agypsum panel of Example 1.

FIG. 6B is a micrograph of a cross-section of the edge region of agypsum panel of Example 1.

FIG. 7 is a graph showing the results of the hydrostatic head tests ofExample 2.

FIG. 8 is a graph showing the results of the hydrostatic head tests ofExample 3.

FIG. 9 is a graph showing the results of the water vapor transmissiontests of Example 4.

DETAILED DESCRIPTION

Disclosed herein are gypsum panels and building sheathing systems havingwater-resistive and air barrier properties, as well as methods of makingand using such panels and systems. These panels and systems provideadvantages over commercially available water-resistive air barriers thatare attached to traditional gypsum sheathing (e.g., mechanicallyattached flexible sheet, self-adhered sheets, fluid-applied membranes,spray foams), as well as over wood-based (e.g., oriented strand board)panels, which do not display the fire-resistance properties of gypsumpanels.

As used herein, the term “water-resistive barrier” refers to the abilityof a panel or system to resist liquid bulk water from penetrating,leaking, or seeping past the sheathing and into the surrounding wallcomponents while also providing a water vapor transmission rate, orpermeance, that is high enough to allow any moisture that does developin the wall to dry. Combined with flashing around openings, suchwater-resistive barriers may create a shingled effect to direct wateraway from the sheathing and surrounding wall components. As used herein,the term “air barrier” refers to the ability of a panel or system toresist the movement of air into (infiltration) and out of (exfiltration)conditioned spaces, to create a more energy efficient structure. As usedherein, the term “water-resistive air barrier” refers to the ability ofa panel or system to display both water-resistive barrier andair-barrier properties.

Gypsum sheathing panels or boards may contain a set gypsum coresandwiched between two fibrous glass mats, one or both of which may becoated. The coating may be a continuous barrier coating. As used herein,the term “continuous barrier coating” refers to a coating material thatis substantially uninterrupted over the surface of the fibrous mat. Thecontinuous barrier coating may be any suitable coating material known tothose of ordinary skill in the art. For example, the coating may includea polymer or resin based binder material along with one or moreinorganic fillers. The continuous barrier coating may be applied on asurface of the fiberglass mat and penetrates some portion of thethickness thereof. For example, a coating may penetrate from about 5percent to about 60 percent of the thickness of a typical fiberglass mat(e.g., about 0.04 mm to about 0.4 mm of a mat having a thickness ofabout 0.4 mm to about 1.0 mm). For example, a coating may penetrate fromabout 20 percent to about 50 percent of the thickness of a typicalfiberglass mat (e.g., about 0.1 mm to about 0.3 mm of a mat having athickness of about 0.5 mm to about 0.8 mm).

During manufacturing, a gypsum slurry may be deposited on the uncoatedsurface of the fiberglass mat and set to form a gypsum core of thepanel. The gypsum slurry may penetrate some remaining fibrous portion ofthe thickness of the fiberglass mat (i.e., some portion of thefiberglass mat that is not already penetrated by the coating) andprovide a mechanical bond for the panel. The gypsum slurry may beprovided in one or more layers, having the same or differentcompositions, including one or more slate coat layers. As used herein,the term “slate coat” refers to a gypsum slurry having a higher wetdensity than the remainder of the gypsum slurry that forms the gypsumcore.

Traditional gypsum sheathing panels do not consistently pass industrystandard bulk water holdout tests and therefore are typically coveredwith commercially available water-resistive air barriers (e.g.,mechanically attached flexible sheets, self-adhered sheets,fluid-applied membranes or coatings, sprayed foams). It has beendetermined that water leaks in these traditional sheathing panels areformed not only because the seams and openings are not treated, but alsobecause water under pressure is able to penetrate though pin holes inthe coating on the fiberglass mat surface and travel through the glassmat along small air pockets or channels underneath the coating and alongthe top of the set gypsum core. This phenomenon is especially noteworthyat or near the edges of the gypsum panel, where open pockets at thegypsum core-glass mat interface are more numerous and voluminous. Theseair pockets, if interconnected, allow water to travel under the glassmat coating, resulting in leaks under treated seams, openings, andfasteners.

Increasing the thickness of the coating material on the fiberglass mathas been found ineffective at providing the desired water-resistive airbarrier, because the extra coating weight results in a greatly reducedwater vapor transmission rate and less potential for drying wet walls inservice. Higher coating weights also increase manufacturing costs andreduce the flexibility of the coated fiberglass mat, making it prone tocracking at the edges.

As such, the present disclosure is directed to providing gypsum panelsand sheathing systems in which such air pockets or voids aresubstantially eliminated, so that the panels display the desiredwater-resistive and air-barrier properties independent of externallyapplied barrier products. Such improved sheathing panels may be combinedwith seaming components (i.e., components that treat the joints, orseams, between panels) to greatly reduce the cost, time, and complexityof installation of a water-resistive air barrier that provides thedesired resistance to bulk water without affecting the water vaportransmission rate of the panel.

While this disclosure is generally directed to gypsum panels, it shouldbe understood that other cementitious panel core materials are alsointended to fall within the scope of the present disclosure. Forexample, cementitious panel core materials such as those includingmagnesium oxide or aluminosilicate may be substituted for the gypsum ofthe embodiments disclosed herein, to achieve similar results.

Improved gypsum panels, building sheathing systems, and methods formaking and using the same are therefore described herein.

Panels and Systems

Gypsum sheathing panels and sheathing systems having water-resistive andair-barrier properties are provided. As shown in FIG. 1, in certainembodiments, a gypsum panel 100 includes a gypsum core 101 that isassociated with a first fiberglass mat 104. The fiberglass mat 104 has abarrier coating 106 thereon, which penetrates a portion of the firstfiberglass mat 104 opposite the gypsum core 101. Gypsum of the gypsumcore 101 penetrates a remaining fibrous portion of the first fiberglassmat 104 such that voids in the first fiberglass mat 104 aresubstantially eliminated.

As used herein, the phrase “such that voids in the fiberglass mat aresubstantially eliminated” and similar phrases refer to the gypsum slurry(e.g., slate coat) filling all or nearly all of the interstitial volumeof the fiberglass mat that is not filled by the coating material. Incertain embodiments, the gypsum of the gypsum core fills at least 95percent of the available interstitial volume of the coated fiberglassmat. In some embodiments, the gypsum core fills at least 98 percent ofthe available interstitial volume of the coated fiberglass mat. Infurther embodiments, the gypsum core fills at least 99 percent of theavailable interstitial volume of the coated fiberglass mat.

Such panels, in which the gypsum penetrates the mat such that the voidsin the mat are substantially eliminated, may be manufactured via avariety of methods, as discussed in more detail herein. For example, thegypsum that contacts the non-coated surface of the fiberglass mat may behydrophobic or otherwise chemically-modified for improved matpenetration, and/or mechanical means may be used to enhance penetrationof the gypsum slurry into the mat.

In certain embodiments, as shown in FIG. 1, the gypsum core 101 includestwo or more gypsum layers 102, 108. For example, the gypsum core mayinclude various gypsum layers having different compositions. In someembodiments, the first gypsum layer 102 that is in contact with thefiberglass mat 104 (i.e., the layer that forms an interface with thecoating material and at least partially penetrates the remaining fibrousportion of the first fiberglass mat) is hydrophobic. In someembodiments, the first gypsum layer has a wet density of from about 88pcf to about 98 pcf. In some embodiments, the first gypsum layer has awet density of from about 93 pcf to about 96 pcf. The first gypsum layermay be a slate coat layer. In some embodiments, the first gypsum layer102 is present in an amount from about 5 percent to about 20 percent, byweight, of the gypsum core 101. The various gypsum layers are shown asseparate layers in the figures for ease of illustration; however, itshould be understood that overlap of these materials may occur at theirinterfaces.

In some embodiments, the slurry that forms the gypsum layer having aninterface with the barrier coating includes a wetting agent tofacilitate penetration of the slurry into the fibrous mat. As discussedin more detail below, the wetting agent may be any agent that reducesthe surface tension of the slurry. In certain embodiments, the firstgypsum layer includes a wetting agent in an amount effective to bring aslurry surface tension of the first gypsum layer to 65 dyne/cm or less.In certain embodiments, the first gypsum layer includes a wetting agentin an amount effective to bring a slurry surface tension of the firstgypsum layer to 60 dyne/cm or less. In certain embodiments, the firstgypsum layer includes a wetting agent in an amount effective to bring aslurry surface tension of the first gypsum layer to 55 dyne/cm or less.In certain embodiments, the first gypsum layer includes a wetting agentin an amount effective to bring a slurry surface tension of the firstgypsum layer to from about 30 dyne/cm to about 55 dyne/cm. In certainembodiments, the first gypsum layer includes a wetting agent in anamount effective to bring a slurry surface tension of the first gypsumlayer to from about 40 dyne/cm to about 55 dyne/cm.

In certain embodiments, as shown in FIG. 2, a gypsum panel 200 includestwo fiberglass mats 204, 212 that are associated with the gypsum core201. The second fiberglass mat 212 is present on a face of the gypsumcore 201 opposite the first fiberglass mat 204. In some embodiments,only the first fiberglass mat also has a continuous barrier coating on asurface thereof. In other embodiments, both fiberglass mats 204, 212have a coating 206, 214 on a surface thereof opposite the gypsum core201. In some embodiments, the gypsum core 201 includes three gypsumlayers 202, 208, 210. One or both of the gypsum layers 202, 210 that arein contact with the fiberglass mats 204, 212 may be a slate coat layerwith hydrophobic characteristics and/or a wet density of from about 88pcf to about 98 pcf, or of from about 93 pcf to about 96 pcf.

The layers of the gypsum core may be similar to gypsum cores used inother gypsum products, such as gypsum wallboard, dry wall, gypsum board,gypsum lath, and gypsum sheathing. For example, the gypsum core may beformed by mixing water with powdered anhydrous calcium sulfate orcalcium sulfate hemihydrate, also known as calcined gypsum, to form anaqueous gypsum slurry, and thereafter allowing the slurry mixture tohydrate or set into calcium sulfate dihydrate, a relatively hardmaterial. In certain embodiments, the gypsum core includes about 80weight percent or above of set gypsum (i.e., fully hydrated calciumsulfate). For example, the gypsum core may include about 85 weightpercent set gypsum. In some embodiments, the gypsum core includes about95 weight percent set gypsum. The gypsum core may also include a varietyof additives, such as accelerators, set retarders, foaming agents, anddispersing agents.

In certain embodiments, one or more layers of the gypsum core alsoinclude reinforcing fibers, such as chopped glass fibers. For example,the gypsum core, or any layer thereof, may include up to about 0.6pounds of reinforcing fibers per 100 square feet of panel. For example,the gypsum core, or a layer thereof, may include about 0.3 pounds ofreinforcing fibers per 100 square feet of panel. The reinforcing fibersmay have a diameter between about 10 and about 17 microns and have alength between about 6.35 and about 12.7 millimeters.

The gypsum core, or one or more layers thereof, such as one or moreslate coat layers, may also include an additive that improves thewater-resistant properties of the core. Such additives may include, forexample, poly(vinyl alcohol), optionally including a minor amount ofpoly(vinyl acetate); metallic resinates; wax, asphalt, or mixturesthereof, for example as an emulsion; a mixture of wax and/or asphalt andcornflower and potassium permanganate; water insoluble thermoplasticorganic materials such as petroleum and natural asphalt, coal tar, andthermoplastic synthetic resins such as poly(vinyl acetate), poly(vinylchloride), and a copolymer of vinyl acetate and vinyl chloride, andacrylic resins; a mixture of metal rosin soap, a water soluble alkalineearth metal salt, and residual fuel oil; a mixture of petroleum wax inthe form of an emulsion and either residual fuel oil, pine tar, or coaltar; a mixture of residual fuel oil and rosin; aromatic isocyanates anddiisocyanates; organopolysiloxanes; siliconates; wax emulsions,including paraffin, microcrystalline, polyethylene, and variousco-emulsified wax emulsions; wax asphalt emulsion, each optionally withpotassium sulfate, alkali, or alkaline earth aluminates, and Portlandcement; a wax-asphalt emulsion prepared by adding to a blend of moltenwax and asphalt, an oil-soluble, water-dispersing emulsifying agent, andadmixing the aforementioned with a solution of case including, as adispersing agent, an alkali sulfonate of a polyarylmethylenecondensation product. Mixtures of these water-resistance additives mayalso be employed. For example, a mixture of two or more of: poly(vinylalcohol), siliconates, wax emulsion, and wax-asphalt emulsion of theaforementioned types, may be used to improve the water resistance of thegypsum core, or gypsum slate coat layer(s) thereof.

The gypsum core, or one or more layers thereof, may also include one ormore additives that enhance the inherent fire resistance of the gypsumcore. Such additives may include chopped glass fibers, other inorganicfibers, vermiculite, clay, Portland cement, and other silicates, amongothers.

In certain embodiments, the fiberglass mat is a non-woven mat of glassfiber that is capable of forming a strong bond with the set gypsum ofthe gypsum core through a mechanical-like interlocking between theinterstices of the fibrous mat and portions of the gypsum core. Bothchopped glass strands and continuous strands may be used. For example,the glass fibers may have an average diameter of from about 10 to about17 microns and an average length of from about ¼ inch to about 1 inch.For example, the glass fibers may have an average diameter of 13 microns(i.e., K fibers) and an average length of ¾ inch. In certainembodiments, the non-woven fiberglass mats have a basis weight of fromabout 1.5 pounds to about 3.5 pounds per 100 square feet of the mat. Themats may each have a thickness of from about 20 mils to about 35 mils.

The strands of the glass fibers may be bonded together to form a unitarymat structure by a suitable adhesive. For example, the adhesive may be aurea-formaldehyde resin adhesive, optionally modified with athermoplastic extender or cross-linker, such as an acrylic cross-linker,or an acrylate adhesive resin.

As discussed above, the continuous barrier coating on the fiberglass matmay be any suitable coating known in the art. For example, the coatingmay include a binder material and, optionally, a filler. In certainembodiments, the coating contains filler in an amount from about 75 toabout 97 weight percent. For example, the coating may contain filler inan amount from about 80 to about 95 weight percent. In one embodiment,the mat coating has a basis weight from about 3 pounds to about 9 poundsof solids per 100 square feet of the fiberglass mat. In certainembodiments, the binder is a polymer material. In certain embodiments,the coating on the first and/or second fiberglass mat is a latex acrylicpolymer containing at least one inorganic filler.

In some embodiments, the binder of the mat coating is a polymer latexadhesive. For example, the binder may be styrene-butadiene-rubber (SBR),styrene-butadiene-styrene (SBS), ethylene-vinyl-chloride (EVCl),poly-vinylidene-chloride (PVdCl) and poly(vinylidene) copolymers,modified poly-vinyl-chloride (PVC), poly-vinyl-alcohol (PVOH),ethylene-vinyl-acetate (EVA), poly-vinyl-acetate (PVA) and polymers andcopolymers containing units of acrylic acid, methacrylic acid, theiresters and derivatives thereof (acrylic-type polymers), such asstyrene-acrylate copolymers.

In one embodiment, the binder is a hydrophobic, UV resistant polymerlatex adhesive. For example, the hydrophobic, UV resistant polymer latexbinder adhesive may be based on a (meth)acrylate polymer latex, whereinthe (meth)acrylate polymer is a lower alkyl ester, such as a methyl,ethyl or butyl ester, of acrylic and/or methacrylic acids, andcopolymers of such esters with minor amounts of otherethylenically-unsaturated copolymerizable monomers (such as styrene),which are known to the art to be suitable in the preparation of UVresistant (meth)acrylic polymer latexes.

In certain embodiments, the coating also includes water and/or otheroptional ingredients such as colorants (e.g., dyes or pigments),transfer agents, thickeners or rheological control agents, surfactants,ammonia compositions, defoamers, dispersants, biocides, UV absorbers,and preservatives. Thickeners may include hydroxyethyl cellulose;hydrophobically-modified ethylene oxide urethane; processed attapulgite,a hydrated magnesium aluminosilicate; and other thickeners known tothose of ordinary skill in the art. For example, thickeners may includeCELLOSIZE QP-09-L and ACRYSOL RM-2020NPR, commercially available fromDow Chemical Company (Philadelphia, Pa.); and ATTAGEL 50, commerciallyavailable from BASF Corporation (Florham Park, N.J.). Surfactants mayinclude sodium polyacrylate dispersants, ethoxylated nonionic compounds,and other surfactants known to those of ordinary skill in the art. Forexample, surfactants may include HYDROPALAT 44, commercially availablefrom BASF Corporation; and DYNOL 607, commercially available from AirProducts (Allentown, Pa.). Defoamers may include multi-hydrophobe blenddefoamers and other defoamers known to those of ordinary skill in theart. For example, defoamers may include FOAMASTER SA-3, commerciallyavailable from BASF Corporation. Ammonia compositions may includeammonium hydroxide, for example, AQUA AMMONIA 26 BE, commerciallyavailable from Tanner Industries, Inc. (Southampton, Pa.). Biocides mayinclude broad-spectrum microbicides that prohibit bacteria and fungigrowth, antimicrobials such as those based on the activediiodomethyl-ptolylsulfone, and other compounds known to those ofordinary skill in the art. For example, biocides may include KATHON LX1.5%, commercially available from Dow Chemical Company, POLYPHASE 663,commercially available from Troy Corporation (Newark, N.J.), and AMICALFlowable, commercially available from Dow Chemical Company. Biocides mayalso act as preservatives. UV absorbers may include encapsulatedhydroxyphenyl-triazine compositions and other compounds known to thoseof ordinary skill in the art, for example, TINUVIN 477DW, commerciallyavailable from BASF Corporation. Transfer agents such as polyvinylalcohol (PVA) and other compounds known to those of ordinary skill inthe art may also be included in the coating composition.

In certain embodiments, a hydrophobic latex or resin material can beincluded in the coating to further improve the water repellence andreduce the water infiltration and enhance bonding between glass mat andgypsum.

Fillers used in the coating may include inorganic mineral fillers, suchas ground limestone (calcium carbonate), clay, mica, gypsum (calciumsulfate dihydrate), aluminum trihydrate (ATH), antimony oxide,sodium-potassium alumina silicates, pyrophyllite, microcrystallinesilica, talc (magnesium silicate), and other fillers known to those ofordinary skill in the art. In certain embodiments, the filler mayinherently contain a naturally occurring inorganic adhesive binder. Forexample, the filler may be limestone containing quicklime (CaO), claycontaining calcium silicate, sand containing calcium silicate, aluminumtrihydrate containing aluminum hydroxide, cementitious fly ash, ormagnesium oxide containing either the sulfate or chloride of magnesium,or both. In certain embodiments, the filler may include an inorganicadhesive binder as a constituent, cure by hydration, and act as a flamesuppressant. For example, the filler may be aluminum trihydrate (ATH),calcium sulfate (gypsum), and the oxychloride and oxysulfate ofmagnesium. For example, fillers may include MINEX 7, commerciallyavailable from the Cary Company (Addison, Ill.); IMSIL A-10,commercially available from the Cary Company; and TALCRON MP 44-26,commercially available from Specialty Minerals Inc. (Dillon, Mont.). Thefiller may be in a particulate form. For example, the filler may have aparticle size such that at least 95% of the particles pass through a 100mesh wire screen.

In certain embodiments, the barrier coating is present on the firstand/or second fiberglass mat in an amount from about 1 pound to about 9pounds, per 100 ft². For example, the coating may be present on thefirst and/or second fiberglass mat in an amount from about 2 pounds toabout 8 pounds, per 100 ft².

In certain embodiments, the panels have a thickness from about ¼ inch toabout 1 inch. For example, the panels may have a thickness of from about½ inch to about ⅝ inch.

By maximizing hydrophobic gypsum slurry penetration into the side of thefiberglass mat receiving gypsum, the movement of water under the matcoating within the glass mat of the finished panel when exposed to bulkwater head pressures may be substantially and adequately reduced,without significantly altering the water vapor transmission rate (i.e.,the ability to dry) of the finished panel. Thus, the gypsum panelsdisclosed herein may have one or more improved water-resistive barrierand/or air-barrier properties.

In certain embodiments, the gypsum panel passes a hydrostatic head testagainst water leakage, as measured by AATCC 127-2008. In addition tohydrostatic head pressure tests, other similar tests can be used toassess bulk water resistance in the range of 0.32 inches water (1.67psf) to 44 inches of water head pressure (228 psf). This may include butis not limited to other water head tests (such as ASTM E2140), waterponding tests, cobb tests (such as ASTM C473, ASTM D 3285, ASTM D 5795,ASTM D7433, ASTM D7281), or a chambered test aided by vacuum or negativepressure differentials. Thus, the gypsum panels described herein maypass any combination of the foregoing tests.

In certain embodiments, the gypsum panel has a water vapor permeance ofat least 10 (inch-pound units per ASTM E96 wet cup method), in the fieldof the panel (i.e., not at the edge of the panel). In some embodiments,the gypsum panel has a water vapor permeance of at least 30 (inch-poundunits per ASTM E96 wet cup method), in the field of the panel. In someembodiments, the gypsum panel has a water vapor permeance of at least 32(inch-pound units per ASTM E96 wet cup method), in the field of thepanel. In certain embodiments, the gypsum panel displays water vaportransmission properties as determined by desiccant methods or by othermethods including high and low relative humidity or dynamic pressurelevels.

In certain embodiments, the gypsum panel displays an air penetrationresistance of 0.02 L/sm² at 75 Pa, or less, when measured according toASTM E2178. In certain embodiments, the gypsum panel displays an airpenetration resistance of 0.02 L/sm² at 300 Pa, or less, when measuredaccording to ASTM E2178.

In certain embodiments, the gypsum panel is fire-resistant. In certainembodiments, the gypsum panel is classified as noncombustible whentested in accordance with ASTM E 136 or CAN/ULC S114 and complies withASTM C1177 requirements for glass mat gypsum substrates designed to beused as exterior sheathing for weather barriers. In particular, a ⅝-inchpanel may have increased fire resistance over other sheathingsubstrates, such as cellulosic-based sheathing. In some embodiments, thegypsum panel has a “Type X” designation, when measured according to ASTME119. The gypsum panels may meet “Type X” designation when tested inaccordance with ASTM E119 fire tests for both generic (Generic systemsin the GA-600 Fire Resistance Design Manual) and proprietary buildingassembly wall designs. ASTM E119 is designed to test the duration forwhich a building assembly can contain a fire and retain structuralintegrity under a controlled fire with a standard time/temperaturescurve. In certain embodiments, the gypsum panel has a level 0 flamespread index and smoke develop index, when measured according to ASTME84. For example, when exposed to surface burning characteristics, perASTM E84 or CAN/ULC-S102, the flame spread index and smoke develop indexfor the gypsum panel may be 0.

Building sheathing systems are also provided herein, and include atleast two of the improved water-resistive air barrier gypsum panelsdescribed herein, including any features, or combinations of features,of the panels described herein. For example, the gypsum panels may eachinclude a gypsum core associated with a first fiberglass mat having abarrier coating, the coating penetrating a portion of the firstfiberglass mat opposite the gypsum core, wherein gypsum of the gypsumcore penetrates a remaining fibrous portion of the first fiberglass matsuch that voids in the first fiberglass mat are substantiallyeliminated.

In certain embodiments, as shown in FIG. 3, a building sheathing systemincludes at least two gypsum panels 300 and a seaming component 320configured to provide a seam at an interface between at least two of thegypsum panels 300.

In certain embodiments, the seaming component comprises tape or abonding material. For example, the seaming component may be a tapeincluding solvent acrylic adhesives, a tape having a polyethylene toplayer with butyl rubber adhesive, a tape having an aluminum foil toplayer with butyl rubber adhesive, a tape having an EPDM top layer withbutyl rubber adhesive, a tape having a polyethylene top layer withrubberized asphalt adhesive, or a tape having an aluminum foil top layerwith rubberized asphalt adhesive. For example, the seaming component maybe a bonding material such as synthetic stucco plasters, cementplasters, synthetic acrylics, sand-filled acrylics, solvent-basedacrylics, solvent-based butyls, polysulfides, polyurethanes, silicones,silyl-modified polymers, water-based latexes, EVA latexes, or acryliclatexes.

Thus, the above-described enhanced panels may be installed with either atape, liquid polymer, or other suitable material, to effectively treatareas of potential water and air intrusion, such as seams, door/windowopenings, penetrations, roof/wall interfaces, and wall/foundationinterfaces. As such, the building sheathing panels, when used incombination with a suitable seaming component, create an effectivewater-resistive and/or air-barrier envelope.

Such building sheathing systems may advantageously pass any or allICC-ES tests required for water resistant and air barrier systemperformance. For example, the sheathing systems may pass Sections 4.1,4.2, 4.3, 4.4, 4.7, and/or 4.8 of the ICC-ES Acceptance Criteria forwater-resistive coatings used as water-resistive barriers over exteriorsheathing (ICC Evaluation Service Acceptance Criteria 212), datedFebruary 2015. For example, the sheathing systems may pass Section 4.5of the ICC-ES Acceptance Criteria for water-resistive membranes factorybonded to wood-based structural sheathing, used as water-resistivebarriers (ICC Evaluation Service Acceptance Criteria 310), dated May2008, revised June 2013.

In certain embodiments, the building sheathing system including at leasttwo gypsum panels and a seaming component displays no water leaks whenmeasured according ICC Evaluation Service Acceptance Criteria 212,Section 4. This test uses an 8′ by 8′ wall assembly built with multiplegypsum panels and having two vertical joint treatments and onehorizontal joint treatment with seaming component(s) (as described inmore detail herein) and flashing treatment with seaming component(s).The wall is subjected to 10 positive transverse load cycles of ASTME2357 (procedure A), to racking loads of ASTM E72 to obtain a netdeflection of ⅛ inch with hold-downs, and then to restrainedenvironmental conditioning cycles as described in AC212 Section 4.7.3for two weeks. Thus, in some embodiments, the building sheathing systemdisplays no water leaks when measured according to ICC EvaluationService Acceptance Criteria 212, Section 4, after being subjected to thetest methods of ASTM E2357 procedure A, ASTM E72, and restrainedenvironmental conditioning. The cycled wall is then tested under ASTME331 water penetration with a water spray of 5 gal/ft²-hr and airpressure differential of 2.86 psf maintained for 15 minutes, andresulting in no leaks within the field of the panel or cracking ofsheathing or seaming components.

Thus, in some embodiments, the building sheathing system displays nowater leaks when measured according to the ASTM E331 wall assembly testat an air pressure of 2.86 psf, 6.24 psf, or even 8.58 psf. The ASTME331 test may be a water spray after a structural test and/or a testincluding the building transitions, openings, and penetrations. Inaddition to ASTM E331, other suitable tests may be substituted, such astests using chambers that spray or flood the exposed side of the wall orare rotated to receive bulk water and create a negative air pressuredifferential on the inside cavity in order to expose leaks. This mayinclude but is not limited to ASTM E547, ASTM D5957, AAMA 501, or fieldtesting apparatus such as ASTM E1105. Thus, the building sheathingsystems described herein may pass any combination of the foregoingtests.

In certain embodiments, the building sheathing system displays an airpenetration resistance of 0.02 L/sm² at 75 Pa, or less, when measuredaccording to ASTM E2178. In certain embodiments, the sheathing systemdisplays an air penetration resistance of 0.02 L/sm² at 300 Pa, or less,when measured according to ASTM E2178.

In certain embodiments, the building sheathing system displays anexfiltration and infiltration air leakage rate of less than 0.04 cfm/ft²at 1.57 lbs/ft² (75 Pa), when measured according to the ASTM E2357 airbarrier assembly test for both opaque walls and walls with penetration,when 8′ by 8′ walls are prepared using seaming components to sealjoints, window openings, duct penetrations, pipe penetrations, externaljunction boxes, and masonry ties. In some embodiments, the ASTM E2357wall assemblies, after being is exposed to Q10>0.20 kPa pressure designvalue wind loads for sustained, cyclic, and gust loads display an airleakage infiltration and exfiltration rate of less than 0.04 cfm/ft² at6.27 lbs/ft² (300 Pa). In certain embodiments, the building sheathingsystem displays an exfiltration and infiltration air leakage rate ofless than 0.02 cfm/ft² at 1.57 lbs/ft² (75 Pa), when measured accordingto the ASTM E2357 air barrier assembly test for both opaque walls andwalls with penetration. In addition to ASTM E 2357, other tests may beused to quantify air leakage in this range, including ASTM E283, ASTME2319, ASTM E1424, ASTM E283, ASTM E1424, or similar test methods. Also,related field testing to test pressure differentials, in this range,such as ASTM E783 or related blower door apparatus testing may also beused. Thus, the building sheathing systems described herein may pass anycombination of the foregoing tests.

In some embodiments, the system passes a hydrostatic head test againstwater leakage, as measured by AATCC 127-2008. In certain embodiments,the building sheathing system passes AATCC hydrostatic head test method127-2008 for a 22-inch head of water (114 psf water pressure) directlyover an interface of at least two gypsum panels and the seamingcomponent, with no leaks after 5 hours. In addition to hydrostatic headpressure, other similar tests can be used to assess bulk waterresistance in the range of 0.32 inches water (1.67 psf) to 44 inches ofwater head pressure (228 psf). This may include but is not limited toother water head tests (such as ASTM E2140), water ponding test, cobbtests (such as ASTM C473, ASTM D3285, ASTM D5795, ASTM D7433, ASTMD7281), or a chambered test aided by vacuum or negative pressuredifferentials. Thus, the building sheathing systems described herein maypass any combination of the foregoing tests.

In certain embodiments, the system passes AC310-2008, which testswater-resistive membranes and barriers. In some embodiments, the systempasses AAMA 714 standard for liquid-applied flashing.

In certain embodiments, the sheathing system has a water vapor permeanceof at least 10 (inch-pound units per ASTM E96 wet cup method). Incertain embodiments, the sheathing system has a water vapor permeance ofat least 20 (inch-pound units per ASTM E96 wet cup method).

Accordingly, the presently described systems are especially effectivealong the edges of the panel, which are traditionally more susceptibleto leaks when installed in a finished system.

Thus, in certain embodiments, the sheathing system (i) passes ahydrostatic head test against water leakage, as measured by AATCC127-2008, (ii) displays no water leaks when measured according to ICCEvaluation Service Acceptance Criteria 212, Section 4, after beingsubjected to the test methods of ASTM E2357 procedure A, ASTM E72, andrestrained environmental conditioning, and/or (iii) displays no waterleaks when measured according to ASTM E331 wall assembly test at an airpressure of 2.86 psf, 6.24 psf, or 8.58 psf. Thus, the sheathing systemmay display certain levels of water resistive properties. Additionally,such sheathing systems may further display desired water vaporpermeance, air penetration resistance, air leakage rate, and fireresistant properties. These sheathing systems therefore provide a waterresistive air barrier in the absence of any externally applied barrierproduct, other than the seaming component. That is, no mechanicallyattached flexible barrier sheet material, self-adhered barrier sheetmaterial, fluid-applied membranes, spray foam membrane, or other barrierproduct need be applied to the external field of the panels to achievethe water-resistive air barrier properties.

Thus, in certain embodiments, the sheathing system includes panelshaving a gypsum core (one or more layers, optionally including one ormore slate coat layers), a fiberglass mat facer, and a mat coatingapplied to the fiberglass mat facer during the panel manufacturingprocess, which panels display the water-resistive air barrier propertiesdescribed herein, independent of any barrier product (e.g., mechanicallyattached flexible barrier sheet material, self-adhered barrier sheetmaterial, fluid-applied membranes, spray foam membrane) being applied tothe external surface of the panel during building construction.

Methods

Methods of making gypsum panels having water-resistive and/or airbarrier properties are also provided. In certain embodiments, methods ofmaking a gypsum panel include depositing a gypsum slurry onto a surfaceof a first fiberglass mat opposite a continuous barrier coating thatpenetrates a portion of the first fiberglass mat, and allowing thegypsum slurry to set to form a gypsum core, wherein the gypsum slurrypenetrates a remaining fibrous portion of the first fiberglass mat suchthat voids in the first fiberglass mat are substantially eliminated.These methods may be used to produce gypsum panels having any of thefeatures, properties, or combinations of features and/or properties,described herein.

For example, the enhanced penetration of the gypsum into the fiberglassmat may be achieved by chemical modification of the gypsum slurry, byuse of a relatively high density gypsum core (or layer(s) thereof),and/or by mechanical means.

In certain embodiments, the gypsum core includes multiple layers thatare sequentially applied to the fiberglass mat, and allowed to seteither sequentially or simultaneously. In some embodiments, a secondfiberglass mat may be deposited onto a surface of the final gypsumslurry layer (or the sole gypsum slurry layer), to form a dual mat-facedgypsum panel. For example, the second fiberglass mat may include abarrier coating on its surface that penetrates a portion of the mat.

The gypsum slurry or multiple layers thereof may be deposited on thefiberglass mat by any suitable means, such as roll coating.

In certain embodiments, depositing the gypsum slurry includes depositinga first gypsum slurry containing a wetting agent, as described in moredetail below. The first gypsum slurry may contain a wetting agent in anamount effective to reduce a surface tension of the first gypsum slurryto 65 dyne/cm or less. In certain embodiments, the first gypsum slurrycontains a wetting agent in an amount effective to reduce a surfacetension of the first gypsum slurry to 60 dyne/cm or less. In certainembodiments, the first gypsum slurry contains a wetting agent in anamount effective to reduce a surface tension of the first gypsum slurryto 55 dyne/cm or less. In certain embodiments, the first gypsum slurryincludes a wetting agent in an amount effective to reduce a surfacetension of the first gypsum slurry to from about 40 dyne/cm to about 55dyne/cm.

In certain embodiments, depositing the gypsum slurry includes depositinga first gypsum slurry having a wet density of from about 88 pcf to about98 pcf onto the surface of a fiberglass mat, the first gypsum slurry. Incertain embodiments, the first gypsum slurry has a wet density of fromabout 93 pcf to about 96 pcf.

In some embodiments, the gypsum core includes at least three gypsumlayers, with the outermost gypsum layers of the gypsum core (i.e., thelayers that form an interface with the fiberglass mats) being slate coatlayers. In certain embodiments, both outermost layers have a relativelyhigh density or are otherwise chemically altered for enhancedpenetration. Thus, a third gypsum slurry may have a wet density of fromabout 88 pcf to about 98 pcf, or from about 93 pcf to about 96 pcf.

In certain embodiments, the first gypsum slurry (or each of theoutermost gypsum slurry layers) is deposited in an amount of from about5 percent to about 20 percent, by weight, of the gypsum core.

In certain embodiments, the gypsum slurry (or one or more layersthereof) includes a wetting agent that functions to reduce the surfacetension of the gypsum slurry. In certain embodiments, the wetting agentis selected from a group consisting of surfactants, superplasticisers,dispersants, agents containing surfactants, agents containingsuperplasticisers, agents containing dispersants, and combinationsthereof. In some embodiments, the wetting agent is present in the gypsumslurry in an amount of about 0.05 percent to about 1 percent, by weight.

Suitable surfactants and other wetting agents are selected fromnon-ionic, anionic, cationic, or zwitterionic compounds, such as alkylsulfates, ammonium lauryl sulfate, sodium lauryl sulfate, alkyl-ethersulfates, sodium laureth sulfate, sodium myreth sulfate, docusates,dioctyl sodium sulfosuccinate, perfluorooctanesulfonate,perfluorobutanesulfonate, linear alkylbenzene sulfonates, alkyl-arylether phosphates, alkyl ether phosphate, alkyl carboxylates, sodiumstearate, sodium lauroyl sarcosinate, carboxylate-basedfluorosurfactants, perfluorononanoate, perfluorooctanoate, amines,octenidine dihydrochloride, alkyltrimethylammonium salts, cetyltrimethylammonium bromide, cetyl trimethylammonium chloride,cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride,5-Bromo-5-nitro-1,3-dioxane, dimethyldioctadecylammonium chloride,cetrimonium bromide, dioctadecyldimethylammonium bromide, sultaines,cocamidopropyl hydroxysultaine, betaines, cocamidopropyl betaine,phospholipids phosphatidylserine, phosphatidylethanolamine,phosphatidylcholine, sphingomyelins, fatty alcohols, cetyl alcohol,stearyl alcohol, cetostearyl alcohol, stearyl alcohols, oleyl alcohol,polyoxyethylene glycol alkyl ethers, octaethylene glycol monododecylether, pentaethylene glycol monododecyl ether, polyoxypropylene glycolalkyl ethers, glucoside alkyl ethers, polyoxyethylene glycol octylphenolethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkylesters, polyoxyethylene glycol sorbitan alkyl esters, sorbitan alkylesters, cocamide MEA, cocamide DEA, dodecyldimethylamine oxide,polyethoxylated tallow amine, and block copolymers of polyethyleneglycol and polypropylene glycol. For example, suitable surfactantsinclude Surfynol 440, Surfynol 465, Surfynol AD01, Surfynol 82, andSurfynol 61, commercially available from Air Products and Chemicals,Inc. (Allentown, Pa.).

In certain embodiments, the gypsum slurry (or one or more layersthereof) includes a hydrophobic additive. For example, the gypsum slurryor layer(s) may include wax, wax emulsions and co-emulsions, silicone,siloxane, silanes, or any combination thereof.

In certain embodiments, the gypsum slurry (or one or more layersthereof) includes a superplasticiser. For example, suitablesuperplasticisers include Melflux 2651 F and 4930F, commerciallyavailable from BASF Corporation.

In some embodiments, the wetting agent is present in the gypsum slurry(or layer(s) thereof) in an amount of 0.05 percent to 1.0, by weight, toreduce the slurry surface tension to about 65 dyne/cm or below, measuredon the aqueous liquid after solid ingredients are filtered out. Incertain embodiments, the surfactant is present in the gypsum slurry (orlayer(s)) in an amount of 0.1 to 0.5 percent, by weight, with theaqueous liquid surface tension in the range between 35 dyne/cm and 55dyne/cm. The reduced surface tension of aqueous liquid in the gypsumslurry enhances the slurry penetration into the glass mat, in referenceto the pure water surface tension of 72 dyne/cm at 25° C.

In certain embodiments, there may be no residual wetting agent presentin the set gypsum panel core.

In certain embodiments, the gypsum slurry (or one or more layersthereof) is substantially free of foam, honeycomb, excess water, andmicelle formations. As used herein, the term “substantially free” refersto the slurry containing lower than an amount of these materials thatwould materially affect the performance of the panel. That is, thesematerials are not present in the slurry in an amount that would resultin the formation of pathways for liquid water in the glass mat of a setpanel, when under pressure.

In certain embodiments, the gypsum slurry (or one or more layersthereof) includes a polymer binder.

In certain embodiments, the first and/or second fiberglass mats arealready coated upon contacting the gypsum slurry. In some embodiments,the methods include applying the coating to the first and/or secondfiberglass mat, either before or after contacting the mats with thegypsum slurry. In certain embodiments, applying the barrier coatingincludes spray coating, ribbon coating, or direct roll coating. In someembodiments, the barrier coating is applied to each of the first and/orsecond fiberglass mats in an amount from about 1 pound to about 9pounds, per 100 ft². For example, the barrier coating may be applied tothe first and/or second fiberglass mat in an amount from about 2 poundsto about 8 pounds, per 100 ft². In other embodiments, coated fiberglassmats may be obtained in a pre-fabricated form.

In certain embodiments, the gypsum slurry (or layers thereof) may bedeposited on the non-coated side of a horizontally oriented moving webof pre-coated fiberglass mat. A second coated or uncoated fiberglass matmay be deposited onto the surface of the gypsum slurry opposite thefirst coated fiberglass mat, e.g., a non-coated surface of the secondcoated fiberglass mat contacts the gypsum slurry. In some embodiments, amoving web of a pre-coated or uncoated nonwoven fibrous mat may beplaced on the upper free surface of the aqueous gypsum slurry. Thus, thegypsum slurry may be sandwiched between two fiberglass mats, one or bothhaving a barrier coating.

In some embodiments, the method also includes mechanically vibrating atleast the first fiberglass mat having the first gypsum slurry depositedthereon to effect penetration of the gypsum slurry into the remainingfibrous portion of the first fiberglass mat. In certain embodiments, themethod includes passing at least the first fiberglass mat having thefirst gypsum slurry deposited thereon over a vibration table. Forexample, a fiberglass mat having only one layer of gypsum slurrydeposited thereon (such as the slate coat), or a fiberglass mat havingmultiple gypsum slurry layers, and optionally a second fiberglass matopposite the first fiberglass mat, may be passed over a vibration table.In certain embodiments, the first fiberglass mat and gypsum slurry arepassed over the vibration table prior to the panel being passed througha forming plate.

In certain embodiments, the vibration table includes at least onevibrating plate configured to display a mean vibration of from about 5in/s to about 10 in/s. In certain embodiments, the vibration tableincludes at least one vibrating plate configured to vibrate at afrequency of from about 32 Hz to about 20 kHz. In some embodiments, thefiberglass mat and gypsum are passed over two sequential vibratingplates. It has been found that compared to traditional rolls having nubsthereon, the vibration tables achieve superior gypsum slurry penetrationof the fiberglass mat.

In certain embodiments, allowing the gypsum slurry to set includesdrying the gypsum slurry, such as in an oven or by another suitabledrying mechanism.

Methods of constructing a building sheathing system, as shown in FIG. 3,are also provided herein, including installing at least two gypsumpanels 300 having an interface therebetween, and applying a seamingcomponent 320 at the interface between the at least two of the gypsumpanels 300. Gypsum panels used in these methods may have any of thefeatures, properties, or combinations of features and/or properties,described herein. Sheathing systems constructed by these methods mayhave any of the features, properties, or combinations or features and/orproperties, described herein. The seaming component may be any suitableseaming component as described herein.

EXAMPLES

Embodiments of the water-resistive air barrier panels disclosed hereinwere constructed and tested, as described below.

Example 1

Fiberglass-faced gypsum panels were manufactured at two plants, inaccordance with the methods disclosed herein, using the compositionshown in Table 1.

TABLE 1 Gypsum Panel Composition for Examples 1 and 2 Component (units)Approximate Amount Stucco (#/MSF) 2200 Accelerator (#/MSF) 6 Dispersant(#/MSF) 2.0 Retarder (#/MSF) 0.3 Water Repellant (#/MSF) 11.5 Water(#/MSF) 1650 Density of Slate Coat (#/ft³) Varied Density of CentralSlurry (#/ft³) 76 Dry Weight (#/MSF) 2630

Hydrostatic head tests (AATCC Test method 127-2008 and ICC AcceptanceCriteria 212) were performed by testing a water column over a treatedjoint area. Tape or a polymer liquid was used to treat the joint betweentwo sample sheathing panels. The seaming component spanned a ¼″ gapbetween the two panel samples and the exterior edges were sealed withwax.

As shown in FIGS. 4A and 4B, a 4-inch (inner diameter) column wassilicone-caulked to the surface so that it completely covered thetreatment area and an untreated panel area on the edge of thetape/liquid polymer. The water column was filled with 21.6″ of water andleft for 5 hours. The water can be dyed and the glass mat peeled back atthe end of the test to assess how much water travel occurred during the5 hours. Water penetration on the back plane of the board or in thejoint is considered a failure. With traditional gypsum panels, watertends to penetrate though the glass mat coating at the very edge of thetape/liquid polymer surface and travel along the glass mat-gypsum slurryinterface to the joint.

The results of the hydrostatic head pressure testing at two differentplants is shown at FIG. 5. The x-axis shows samples taken every 3″across the board width from code (timecode) edge to non-code edge. They-axis indicates the distance of water travel at the interface area ofthe glass mat and slurry slate coat. A value of 1.5″ indicates a leakingspecimen where water has made it all the way to the joint. Plant 1 had aslate coat wet density of 95 pcf and used electric vibration tables.Plant 2 had a slate coat wet density average of 87.5 pcf and usedtraditional vibrator rolls. Also shown is Plant 2 with no slate coat. Asis illustrated by the graph, the higher density slate coat incombination with the electric vibrator tables resulted in moreconsistency in passing hydrostatic head test, especially near the edgeof the panel. No slate coat resulted in very inconsistent performance.

FIGS. 6A and 6B are micrographs showing the cross-section of the slatecoat sample made at plant 2, at the center and edges of the panel,respectively. These micrographs reveal good penetration of high densityslurry near center of board.

Example 2

In another experiment, Test Sheathing A was made having the compositionshown in Table 1, wherein the sheathing had a high slate coat density of93 pcf. Two inline electric vibration tables manufactured by VIBCO(Wyoming, R.I.) mounted on isolation pads were adjusted to 33.5 Hz onthe first table and 45.5 Hz on the second table, allowing for completeslate coat penetration without bleed-through. The glass mat inline mattension was increased by increasing the brake pressure on the mat rollunwinder.

Test Sheathing B was also prepared according to the composition of Table1 and had a slate coat density of approximately 88 pcf and usedtraditional vibrating rollers during panel manufacture. Both plants hadthe same relative amount of hydrophobic additives in the slate coat.Observations made with a 1× Nikon hand lens showed consistent slate coatpenetration for Sheathing A while Sheathing B's penetration variedconsiderably.

As shown at FIG. 7, when tested in hydrostatic head pressure testing of22″ water column for 5 hours, all of the Sheathing B specimens leaked bywater traveling underneath the mat surface while Sheathing B specimensshowed no signs of leaks. The percentage weight gain was calculated andshowed an average weight gain of 0.86% for Sheathing A and 3.0% forSheathing B. It is believed the 5-hour percent weight gain inhydrostatic head of Sheathing A could be even further reduced byincreasing the hydrophobic additive percentage in the slate coat.

Also, as shown in FIG. 7, commercially available gypsum glass matproducts were purchased and tested using the same sampling procedure andtest method used for Sheathings A and B. Industry Products 1-5 werecommercially available gypsum glass mat sheathing products with a coatedglass mat while Industry Product 6 was a gypsum glass mat sheathingproduct that claims >70% embedded glass mat in the gypsum face.

Results showed that Sheathing A displayed better water resistance thanknown coated glass mat sheathing products. Sheathing A also showedsignificantly better results compared to gypsum sheathing with anembedded mat (Industry Product 6) as 2 out of 10 specimens leakedcompared to 0 out of 10 leaking for Sheathing A. The percent weight gainof Industry Product 6 in hydrostatic head over 5 hours was significantlyhigher at 5.6% compared to 0.8% for Sheathing A. It is believed thateven though the mat claims 70% embedded glass mat, the unembeddedportion covered with coating, density, properties of the gypsum, and/orlack of mechanical or chemical means of saturating the mat createsundesirable voids in the gypsum mat surface area, leading to leakage.

Example 3

A laboratory experiment was also conducted, in which five 12″×12″ panelswere manufactured, having the compositions shown in Table 2.

TABLE 2 Gypsum Panel Compositions for Example 3 Surfactant Slate Gypsum(Surfynol) in Coat Wet Core Wet Water Slate Coat Slump Slate CoatDensity Density Water:Stucco Repellant Condition (in) (%) (pcf) (pcf)Ratio (#/MSF) 95 pcf w/o 12.5 0 95 93 0.8 0 hydrophobic additive 95 pcf12.5 0 95 93 0.8 11.1 95 pcf + 0.1% 13.5 0.1 97 93 0.8 11.1 Surfynol 83pcf 11.5 0 83 93 0.8 11.1 83 pcf + 0.1% 10.5 0.1 84 93 0.8 11.1 Surfynol

The glass mats were slate coated before adding the core slurry, and nomechanical means (e.g., vibration) were used to increase slurrypenetration. Hydrostatic head tests in accordance with those describedwith reference to Example 1 were performed. FIG. 8 is a graph showingthe water travel under the coating in inches for five samples.

The results of this Example show that control panels without ahydrophobic additive (e.g., silicone) in the slurry failed thehydrostatic head test within the first 30 minutes, resulting in leakingat the joint. Slate coats with higher wet densities (e.g., 95 pcf) hadbetter results than lower densities (e.g., 83 pcf). Adding a surfactant(e.g., Surfynol) to the slate coat resulted in significantly betterpenetration and hydrostatic head pressure test results, even at thelower densities.

Example 4

Water Vapor Transmission Testing according to ASTM E96 wet cup methodwas conducted for various liquid membrane products that were appliedaccording to the manufacturer's instructions over ⅝″ by 12″ by 12″DENSGLASS® sheathing (manufactured by Georgia Pacific, Atlanta, Ga.).Sheathing A, per Example 2, was also tested without additionaltreatments. The four liquid membrane products were standard materialsused in the industry and purchased from a water proofing distributer.The liquid membrane products were applied across the entire field of theDENSGLASS sheathing panels with a straight edge panel according to themanufacturers' recommended usage rates, Liquid Membrane 1=10 wet mils,Liquid Membrane 2=70 wet mils, Liquid Membrane 3=60 wet mils, and LiquidMembrane 4=10 wet mils.

As shown in FIG. 9, the permeance of Sheathing A was substantiallyhigher than the permeance of the liquid membranes applied over glass matsheathing (4.8 to 8.1 perms versus 31.6 perms), indicating the higherdrying potential for such sheathing panels in-service.

Example 5

A time motion study was conducted to determine the time savingsassociated with the disclosed sheathing barrier system versuscommercially available alternatives. Specifically, a three-storycommercial building having a height of 28 feet, a total wall length of88 feet, and a total of 2,464 gross square feet of sheathed exteriorwall area was constructed. The building included 12 window openings andtwo door openings as well as a combination of outside and insidecorners, to replicate a realistic commercial construction setting. Anexperienced water and air barrier installation crew installed fourdistinct barrier systems, including window and door flashing suitablefor non-flanged commercial windows and doors, on one half of thebuilding (i.e., approximately 1,126 net square feet of sheathed areawith one door and six window openings), according to the manufacturers'installation guidelines for non-flanged windows, including coating theinside door and window openings with a fluid-applied sealant or flashingtape.

The first system included building wrap fastened with a pneumatic capstapler to the sheathing panels. All wrap seams were overlapped andsealing with 2.5 inch tape. 6 inch self-adhesive flashing was applied toall window and door openings. The total installation time was 8 hoursand 31 minutes. The second system included fluid sealant applied via afluid gun onto fastener heads and panel seams of the sheathing system,fluid sealant applied via a fluid gun to fully flash one door and sixwindow openings, and fluid sealant applied by roller onto the entireexterior surface of the sheathing panels. The total installation timewas 10 hours and 41 minutes.

The third and fourth systems included water-resistive air barriersheathing panels as disclosed herein. In the third system, 4-inchself-adhesive flashing was applied to the sheathing seams and corners,fluid sealant was applied to fastener heads, and 6 inch self-adhesiveflashing was applied to all wind and door openings. The totalinstallation time was 6 hours and 22 minutes. In the fourth system,fluid sealant was applied to all fastener heads, seams, and door/windowopenings. The total installation time was 6 hours and 26 minutes. Thus,installation of the sheathing systems including the water-resistive airbarrier sheathing panels disclosed herein was accomplished insignificantly less labor time as compared to known commercial buildingwrap and fluid sealant systems.

Thus, the gypsum sheathing panels and building sheathing systemsdisclosed herein display water-resistive and air-barrier properties thatwere previously achieved in gypsum panels only through attachingseparate water-resistive air barriers (e.g., mechanically attachedflexible sheet, self-adhered sheets, fluid-applied membranes, sprayfoams) thereto. Because gypsum panels display fire-resistanceproperties, these panels and systems provide advantages over wood-based(e.g., OSB) panels.

In these gypsum panels and sheathing systems, air pockets or voids aresubstantially eliminated, so that the panels display the desiredwater-resistive barrier and air-barrier properties independent ofexternally applied barrier products. These improved sheathing panels maybe combined with seaming components (i.e., components that treat thejoints, or seams, between panels) to greatly reduce the cost, time, andcomplexity of installation of a water-resistive air barrier thatprovides the desired resistance to bulk water without affecting thewater vapor transmission rate of the panel. Accordingly, the disclosedsystem advantageously eliminates the need for applying further materialsto a gypsum panel (e.g., either a membrane or liquid/foam material) toachieve water-resistive air barrier properties, when the seams aretreated, and also provides fire resistance.

While the disclosure has been described with reference to a number ofembodiments, it will be understood by those skilled in the art that theinvention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions, or equivalent arrangements not describedherein, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A method of constructing a building sheathingsystem, comprising: installing at least two gypsum panels having aninterface therebetween to form an external building sheathing; andapplying a seaming component at the interface between the at least twogypsum panels, wherein, in the absence of any externally applied barrierproduct, other than the seaming component: the system passes ahydrostatic head test against water leakage, as measured by AATCC127-2008, the system displays no water leaks when measured according toICC Evaluation Service Acceptance Criteria 212, the system passes ICCEvaluation Service Acceptance Criteria 310, and/or the system displaysno water leaks when measured according to ASTM E331 wall assembly test,wherein the at least two gypsum panels each comprise a gypsum coreassociated with a first fiberglass mat having a continuous barriercoating that comprises a plurality of pin holes that provide for watervapor transmission across the coating, the coating penetrating a portionof the first fiberglass mat opposite the gypsum core, wherein gypsum ofthe gypsum core penetrates a remaining fibrous portion of the firstfiberglass mat such that voids in the first fiberglass mat aresubstantially eliminated, and wherein the gypsum core of each gypsumpanel comprises a first gypsum layer that at least partially penetratesthe remaining fibrous portion of the first fiberglass mat, the firstgypsum layer being formed by a gypsum slurry that comprises a wettingagent in an amount effective to bring a slurry surface tension of thefirst gypsum layer from about 30 dyne/cm to about 55 dyne/cm.
 2. Themethod of claim 1, wherein the gypsum core of each gypsum panelcomprises a first gypsum layer that at least partially penetrates theremaining fibrous portion of the first fiberglass mat, the first gypsumlayer having a slurry density of about 88 pcf to about 98 pcf.
 3. Themethod of claim 1, wherein the first gypsum layer is present in anamount from about 5 percent to about 20 percent, by weight, of thegypsum core.
 4. The method of claim 1, wherein the seaming componentcomprises tape or a bonding material.
 5. The method of claim 4, whereinthe seaming component comprises a bonding material selected from thegroup consisting of synthetic stucco plasters, cement plasters,synthetic acrylics, sand-filled acrylics, solvent-based acrylics,solvent-based butyls, polysulfides, polyurethanes, silicones,silyl-modified polymers, water-based latexes, EVA latexes, and acryliclatexes.
 6. The method of claim 1, wherein the system passes AATCChydrostatic head test method 127-2008 for a 22-inch head of waterdirectly over the seaming component at the interface between the atleast two gypsum panels, with no leaks after 5 hours.
 7. The method ofclaim 1, wherein the system has a water vapor permeance of at least 20inch-pound units, as measured by ASTM E96 wet cup method.
 8. The methodof claim 1, wherein the system displays an air leakage rate of less than0.04 cfm/ft² at 1.57 lbs/ft², when measured according to ASTM E2357. 9.The method of claim 1, wherein the system is substantially free of anyexternally-applied fabric membrane, liquid coating, or self-adheredmembrane.
 10. A method of constructing a building sheathing system,comprising: installing at least two gypsum panels having an interfacetherebetween to form an external building sheathing, each gypsum panelcomprising a gypsum core associated with a first fiberglass mat having acontinuous barrier coating that comprises a plurality of pin holes thatprovide for water vapor transmission across the coating, the coatingpenetrating a portion of the first fiberglass mat opposite the gypsumcore, wherein gypsum of the gypsum core penetrates a remaining fibrousportion of the first fiberglass mat such that voids in the firstfiberglass mat are substantially eliminated; and applying a seamingcomponent at the interface between the at least two gypsum panels,wherein the system is substantially free of any externally-appliedfabric membrane, liquid coating, or self-adhered membrane, and whereinthe gypsum core of each gypsum panel comprises a first gypsum layer thatat least partially penetrates the remaining fibrous portion of the firstfiberglass mat, the first gypsum layer being formed by a gypsum slurrythat comprises a wetting agent in an amount effective to bring a slurrysurface tension of the first gypsum layer from about 30 dyne/cm to about55 dyne/cm.
 11. The method of claim 10, wherein the gypsum core of eachgypsum panel comprises a first gypsum layer that at least partiallypenetrates the remaining fibrous portion of the first fiberglass mat,the first gypsum layer having a slurry density of about 88 pcf to about98 pcf.
 12. The method of claim 10, wherein the first gypsum layer ispresent in an amount from about 5 percent to about 20 percent, byweight, of the gypsum core.
 13. The method of claim 10, wherein theseaming component comprises tape or a bonding material.
 14. The methodof claim 13, wherein the seaming component comprises a bonding materialselected from the group consisting of synthetic stucco plasters, cementplasters, synthetic acrylics, sand-filled acrylics, solvent-basedacrylics, solvent-based butyls, polysulfides, polyurethanes, silicones,silyl-modified polymers, water-based latexes, EVA latexes, and acryliclatexes.
 15. The method of claim 10, wherein the system passes AATCChydrostatic head test method 127-2008 for a 22-inch head of waterdirectly over the seaming component at the interface between the atleast two gypsum panels, with no leaks after 5 hours.
 16. The method ofclaim 10, wherein the system has a water vapor permeance of at least 20inch-pound units, as measured by ASTM E96 wet cup method.
 17. The methodof claim 10, wherein the system displays an air leakage rate of lessthan 0.04 cfm/ft² at 1.57 lbs/ft², when measured according to ASTME2357.